The Bird Mating Season - Why Spring?

When Birds Mate

Baltimore Oriole in Spring
Spring is the mating season for most birds. - Photo © Jen Goellnitz

The breeding season is an ideal time for birding. Knowing when bird mating season is at its peak can help birders plan to attract nesting birds to their backyard, visit isolated leks to see rare species or just enjoy the beauty of courting birds.

Breeding Season Timing

Birds do not mate for pleasure, only for procreation, and many male birds are sterile outside the breeding season. The exact timing of when bird pairs come together for successful mating varies, and the timing evolves for different species to give the resulting chicks the best chance of survival.

Factors that affect the bird mating season include:

  • Geography: The farther north a bird’s breeding range is located, the later its mating season will begin. These birds may migrate earlier, however, because they have greater distances to travel in order to reach their ideal breeding locations. They may also have shorter incubation or parenting periods to account for the shorter productive breeding seasons.
  • Food: A greater availability of easily accessible food is essential for parent birds to provide adequate nutrition for their chicks. This is why birds migrate before the breeding season. Moving to a different area where food is abundant helps spread out their population so they will have a better chance of properly feeding their young.
  • Water: In dry deserts or other arid habitats, the sudden appearance of water through seasonal storms or flooding can trigger the mating season. In those types of habitats, plants have evolved to quickly bloom when water is available, and those plants provide the necessary food for birds to raise chicks. As a result, many desert birds have more flexible mating seasons.
  • Brood Numbers: If a bird species raises multiple broods each year, the mating season typically begins earlier so there is plenty of time for each brood to be cared for as the eggs are incubated and the chicks mature. Birds that can raise multiple broods may not always have a second or third brood, however, if conditions are not favorable for the chicks to survive. Mortality rates are also often higher in later broods, and not all chicks will live.
  • Nesting Sites: Where a bird builds a nest can affect the time it mates. Cavity-nesting species that reuse the nest cavities of other birds may breed later in the season so more nesting sites have already been abandoned after earlier successful nests. Birds that build new nests each year may also nest later in the season, so they have enough time to gather materials to create their nests. Birds that reuse old nests each year can mate earlier and still have a suitable location to raise their young.

Signs of the Mating Season

Spring is the typical mating season for most bird species. At that time food sources are increasing, melting snows and spring rains provide plenty of water and there will be a long, temperate season for birds to mature before winter arrives.

But just like spring migration varies in different areas and for different species, when birds mate in spring also varies. Birders can watch for signs of the breeding season, however, to learn when local birds are feeling reproductive urges.

To pinpoint when the bird mating season occurs, watch for:

  • Warming temperatures and blooming flowers that show the change of seasons.
  • Birds claiming territory and becoming more aggressive toward intruders, particularly males.
  • The appearance of bright breeding plumage with fresh, clear markings.
  • Increased bird song, which can help define territories and attract mates.
  • Bird courtship behavior, including elaborate display flights and other bonding.
  • Dissipation of large winter flocks or mixed foraging flocks as birds pair off with mates.
  • The collection of nesting materials and the beginning of nest building activities.

    The nesting season may be a few weeks long for each species as they claim a territory, attract a mate and raise one or more broods of chicks. The actual mating period for birds, however, may last only a week or two as individuals are receptive to the act of copulation, and the mating itself may be just a few seconds or minutes.

    Birding During Breeding Season

    The breeding season is one of the most popular times for birding because while birds are defending territories and attracting mates, they are very colorful and visible for birders to see. Many birding festivals are planned to take advantage of spring migration, and some field trips or tours may carefully visit leks or rookeries to observe birds without disturbing them.

    Birders who know the signs of the mating season can also enjoy local birds. Backyard birders who are aware of the breeding season can plan when to put up bird houses, attract birds with nesting materials or begin watching for the appearance of chicks. At the same time, birders should take appropriate steps to safeguard mating birds, such as minimizing the use of bird call recordings that could stress or distract birds. Discouraging feral cats and keeping bird houses safe will also protect breeding birds in the backyard.

    When birds mate is all about survival. Knowing when the bird mating season occurs and how to be a responsible birder during that time period is a great way to help birds begin each new family with the best chance for the chicks to survive. The more chicks that survive, the better successive breeding seasons will be as more birds take advantage of the best conditions to start each new generation.